In the carton production process, a printer slotter is used for printing on corrugated fiberboards and die-cutting and creasing the boards.
FIGS. 6 and 7 show a sheet feeder for use in feeding corrugated fiberboards, i.e., sheets, to the printer slotter.
The sheet feeder includes a fixed gate 4 disposed at the front end of a base 1, and a movable guide plate 41 positionable in place and movable toward and away from the fixed gate. Thick sheets S stacked up between the fixed gate 4 and the movable guide plate 41 are kicked out toward the printer slotter one by one from the lowermost position of the stack by a kicker 10 and a suction device (not shown) on the base 1.
The kicker 10 has a kicker plate 14 slidably provided on the base 1 and reciprocatingly movable by a crank 9. When the kicker plate 14 advances toward the fixed gate 4, an engaging portion 15 of the plate 14 engages the rear end of the lowermost sheet to kick out the sheet. Usually, the suction device applies suction at least locally on the lower surface of the lowermost sheet so that the sheet can be smoothly kicked out even if warped.
The kicker plate 14 and the movable guide plate 41 are coupled to positioning mechanisms 7, 70, respectively, for positioning these plates in place on the base 1 with respect to the direction of feed of the sheet in accordance with the width of the sheet.
The positioning mechanism 70 for the movable guide plate 41 comprises a pair of parallel screw rods 43, 43 arranged on opposite sides of the base 1 and coupled to drive means (not shown). The screw rod 43 extends through, and is in screw-thread engagement with, a leg 42 projecting from each end of the movable guide plate 41.
When the screw rods 43 are rotated in a positive or reverse direction as required, the movable guide plate 41 can be brought to the desired position by the thrust of screw.
Like the positioning mechanism 70 for the guide plate 41, the positioning mechanism 7 for the kicker plate 14 utilizes screw thrust, whereas since the kicker plate 14 as positioned in place needs to move reciprocatingly for kicking out sheets, the entire positioning mechanism 7 is reciprocatingly movable with the kicker plate 14. Screw rods 17, 17 are slidably and rotatably arranged in parallel to the screw rods 43, 43 inwardly thereof. The screw rod 17 extends through, and is in screw-thread engagement with, a leg 16 projecting from the kicker plate 14.
A gear 18 is mounted on a front portion of the screw rod 17. A spline shaft 95 disposed below the screw rod 17 slidably carries thereon a drive gear 94 meshing with the gear 18 on the screw rod 17. A support plate 93 is rotatably fitted around the boss of the drive gear 94 and is movable with the drive gear 94 axially of the spline shaft 95. The support plate 93 has an upper end supporting the front end of the screw rod 17.
The crank 9 for reciprocatingly driving the kicker plate 14 is connected to a lever 91 by a link 90. The lever 91 has a free end which is connected to the support plate 93 by a link 92.
The kicker plate 14 is reciprocatingly moved relative to the base 1 to kick out the sheets S one by one by the rotation of the crank 9 which is transmitted through the link 90, lever 91, link 92, support plate 93, screw rod 17 and leg 16.
The spline shaft 95, when rotated, causes the drive gear 94 and the gear 18 to rotate the screw rod 17, advancing or retracting the leg 16, i.e., the kicker plate 14, whereby the kicking start position of the kicker plate 14 can be adjusted in accordance with the size of the sheet S.
The amount of kicking-out of the sheet S by the kicker plate 14 corresponds to the distance from the fixed gate 4 to feed rollers 81, 81 of the printer slotter. When delivered to the feed rollers 81, 81, the sheet S is transported toward a plate cylinder 82 by the rotation of the feed rollers 81, 81 for printing.
However, the movable guide plate 41 must be held in a position after the position has been determined with respect to the feed direction, and the kicker plate 14 needs to be reciprocatingly movable from a position which has been determined with respect to the feed direction. It is therefore impossible to use a single system for driving both the positioning mechanism 70 for the movable guide plate 41 and the positioning mechanism 7 for the kicker plate 14. Accordingly, the conventional feeder has the problem of being complex in the construction of the drive systems used.
Further in the case where the kicker plate 14 is reciprocatingly driven by the crank 9, the sheet S is delivered to the rollers 81, 81 at the moment when the speed of movement of the kicker plate 14 is greatest. During one turn of rotation of the crank 9, about 1/4 of the rotation is then effectively utilized for feeding the sheet S, hence a low efficiency. Additionally, the actual stroke length of the kicker plate 14 needed is about twice the distance from the kicking-out start position to the nip of rollers 81, 81. This results in the drawback that the lever 91 must be made swingingly movable over a large distance.
The conventional feeder has another drawback. The arrangement wherein the support plate 93, the drive gear 94 and the screw rod 17 are moved with the kicker plate 14 requires a large means (not shown) for rotating the crank 9, consequently producing increased vibration during the reciprocating movement of the kicker plate 14.
While the sheet is delivered to the rollers 81, 81 approximately when the speed of kicking-out of the sheet by the kicker plate 14 is the highest, it is likely that the sheet will be propped against the nip of the rollers 81, 81 by the kicker plate 14. This must be prevented by causing the rollers 81, 81 to pull out the sheet S at a higher speed than the kicking-out speed of the kicker plate 14.
The present invention, which has been accomplished in view of the above situation, provides a sheet feeder which is adapted to kick out sheets by belts having kicker members and movable in revolution in a fixed position instead of the reciprocatingly movable kicker plate so that the sheet can be kicked out with a small torque and with diminished vibration, the sheet feeder having a simplified mechanism for positioning the kicker members and a movable guide plate in place with respect to the direction of feed of the sheet.